Belt conveyors that comprise a transporting belt with an upper advancing portion (upper strand) and a lower returning portion (lower strand) are generally known. For this purpose, the belt conveyors usually have a sliding table, which forms a support and on which the load-bearing strand slides. Such conveying devices are used for transporting items and/or people, for example in automobile construction as a “worker-rider belt” running parallel to the actual assembly line.
It is known to mount a sliding table, on which the upper strand runs, with a lower sliding surface on the lower strand in a floating manner. The lower strand is in turn mounted in a sliding manner with respect to the base, specifically by means of a fixed sliding table. In the case of this prior art, the force of the weight of the load is therefore directed over the surface area by the returning lower strand.
DE 10 2005 041 523 A1 proposes as a development of this prior art additionally providing a co-running auxiliary belt between the lower strand and the base.
DE 10 2004 002 738 A1 discloses a belt conveyor of which the upper strand is mounted by means of a sliding table, which is supported on a supporting frame that rests for example on the ground. The (unloaded) lower strand is mounted in a rolling manner by supporting rollers.
In this case, the load-bearing side is optimized with regard to whatever is being transported and also the desired chemical, physiological and mechanical properties of the belt by various coating materials, thicknesses and structures.
The suitability for use is greatly influenced by the tension member and the fabric used for it, for example a polyester fabric. In particular, they determine the belt running properties, the stress/strain characteristics, the electrostatic properties, the flatness and the knife-edge and curve inclination.
The running side and its properties essentially determine the noise emission, the energy consumption and also the wear and the usability for the sliding support of the transporting belt.
The load-bearing side and the running side may be realized for example by coatings of plastic or elastomer, innumerable variants being feasible for different types of transporting belt and configurations and the various practical requirements.
In practice, measures for realizing optimum friction pairings, and thus allowing energy-saving and environmentally friendly operation, have already been successfully developed. As a result, the operating costs are reduced by the lower friction coefficient, so that at the same time the drive power that is required during operation can also be reduced. Furthermore, reduced noise emissions, and consequently improved working conditions, are thereby obtained during operation. In addition, long service lives are achieved.
Providing the running-side fabric with a sliding layer that acts permanently as a dry lubricant has the effect of minimizing the energy demand.
The low friction coefficient with respect to the table has the effect of lowering the drive power that has to be effectively transferred.
A transporting belt with the aim of reducing friction is for example also known from EP 2 259 989 B1. The transporting belt has a first fabric layer and a second fabric layer of a polyester fabric, which between them enclose a composition that contains polyurethane, polyvinylchloride and a flame retardant.
Furthermore, EP 1 281 639 B1 discloses a perforated belt, preferably of metal, with an applied nonstick coating, which comprises PTFE (polytetrafluoroethylene), silicone or nanoparticles.